I. Field of the Invention
The present invention relates generally to the manual lifting and stacking of containers such as drums, barrels, canisters, or the like, particularly in close quarters where room does not permit manipulation by mechanized devices, but where the size and weight density are such that two persons are required to perform the lifting and placement operation and the operation is also logistically difficult, i.e., the two individuals must grapple with each container totally by hand. Problems are especially acute where storage capacity and transportation efficiencies require a plurality of layers of containers to be provided. The present invention provides a manual lifting device of relatively simple construction that is safely and easily operated by two persons. The lifting device has particular application in the manufacture and storage of munition propellant materials which are typically stored in cylindrical fiber drums which may need to be stacked and unstacked several times in close quarters.
II. Related Art
In the past, containers or canisters such as fiber drums containing processed propellant materials have been stored and moved in single-layer fashion manually loaded by two individuals who lift and place them on pallets. The pallets have been addressed by forklifts which stack them for storage or shipment. This method has several drawbacks, however, housing efficiency is reduced due to lost storage space, both on the pallets and in the storage buildings where much additional room has to be provided for the operation of the forklifts. Also, there are reduced efficiencies in the transportation of the materials because trucks transporting the product from the pack-out facilities have been limited to loading a single pallet layer in many cases because of lack of available room at destination buildings. Furthermore, additional manpower and time may be required if it is necessary to transport forklifts back and forth between storage buildings. Moreover, owing to the hazardous nature of the product being moved, the forklifts (or any other mechanized devices) used have to be rated to meet the hazards classification of the storage facility.
Known canister/barrel lifting devices also include manual jacks, hydraulic lifts and electric lifts and, while they can be used, they also introduce the same or similar types of inefficiencies and problems to the operation including space requirements and the need to meet hazardous classification requirements, particularly in the case of powered devices.
There has remained a need to provide a more efficient and user-friendly device to enable a pair of operators to lift and stack canisters or drums of the class in a limited space with a minimum of physical stress.